1. Technical Field of the Invention
This invention relates generally to sun glare on a vehicular windshield, and more particularly to providing a method for the calculation of the sun glare position and a system for displaying a darkened area in the windshield to reduce the intensity of the sun glare or to block the sun glare from the driver's eyes.
2. Description of the Related Art
Sun glare is one of the most overlooked dangers of driving. It causes fatal accidents and injuries, creates highway havoc, and drastically slows traffic. The situation is worst during the height of morning and evening commutes for east- and west-bound traffic, respectively. When the sun directly perches on the horizon, a sudden, direct flash of sunlight lasting a mere decisecond can easily blind the driver. Considering the significant potential impacts of sun glare on drivers, many systems and methods of reducing or blocking sun glare have been presented in the past two decades. The most relevant arts prior to this invention are described in the following paragraphs.
Many visor extensions are available on the market and/or have been patented. Some are manual and others are automatic (U.S. Pat. No. 5,271,653, December 1993, Shirley; U.S. Pat. No. 6,286,887 B1, September 2001, Hashmi; U.S. Patent Application 2002/0130530, September 2002, Zenisek; U.S. Pat. No. 7,163,252 B1, January 2007, Neault; U.S. Pat. No. 4,923,238, May 1990, Morgulis, Tilman, Shemes). However, these visor extensions provide protection only if the sun glare is in the top region of the windshield and they may obstruct the driver's view. When the area of intense sun glare lies in the lower region of the windshield, the driver has to raise one hand to shield the sun's piercing light and keep only one hand on the steering wheel, causing a dangerous situation.
A number of inventions consist of manual laterally movable sun visors. Although these visors can move in both the vertical and horizontal directions, they still have the shortcomings of a visor because they are inconvenient and may divert the driver's attention away from the road. A movable visor that is automatically positioned laterally across the windshield and extended downward is documented in U.S. Pat. No. 4,874,938. The positioning is based on the azimuth and elevation of the sun and the angle of the sun's direction relative to the driver's eyes. Angles are detected by a complicated detection system, and the positioning requires a sophisticated motor and cable system. Although the positioning is automatic and may be accurate, the invention has the shortcomings of a visor and the system requires significant hardware additions and modifications. Other forms of sun glare shields are also available, such as an extendable sliding shield of polarized material having a black glass coating (U.S. Pat. No. 5,513,892, May 1996, Thomas). However, these also require extensive hardware addition and modification and obstruct the driver's view.
Another group of inventions employs electrochromatic elements whose transparency can be varied according to the amount of electric voltage or current applied. Some inventions involve coverings over the entire area of the windshield while others restrict the change in opacity in only the upper region, certain fixed sections, or shading bands of the windshield. Several more advanced inventions incorporate changes in opacity of the windshield from the top edge throughout the entire windshield in a propagating manner, such as in U.S. Patent Application 2007/0133078 A1. However, none of the aforementioned systems provide a method that is automatic or darkens only a specific area in the windshield needed to block the sun glare. Another related invention is an anti-dazzle device, installed between the driver and the windshield, with optical sensors that will darken the electro-sensitive screen as documented in U.S. Pat. No. 5,258,607. Although it is automatic with an optical sensor, the device is cumbersome. All the inventions noted in this paragraph unnecessarily darken areas of the windshield that are not in the path of the sun glare to the driver's eyes, which will inadvertently obstruct the driver's view.
An electrochromatic visor that darkens based on the intensity of sunlight detected, consisting of a sophisticated light-detecting apparatus for monitoring sunlight incident upon the face of the driver, is documented in U.S. Pat. No. 6,811,201 B2. The system can darken a specific required area in the visor. However, this invention has the limitation of a visor; a visor fulfills its purpose only if the sun glare is viewed in the top region of the windshield. It also requires a sophisticated digital camera and sensor system. A window pane with a visor-like segment and a glare sensor measuring the eye position of the driver is documented in DE 102005007427A1. The transparency of the segment can be adjusted based on the output signal of the glare sensor. Similar to the visor, the visor segment only serves its purpose when the sun glare area is in the top region of the windshield, and the invention requires a sophisticated glare sensor system.
An electrochromic windshield that can have a specific darkened section controlled by the driver is documented in U.S. Pat. No. 4,892,394. However, the only mode of control is manual through a touch pad that allows up-down and left-right relocation of the section. Since the system is not automatic, it will divert the driver's attention away from the road. Another invention for blocking sun glare incorporates a liquid crystal film as documented in JP 2003159942A2. The light permeability of its specific area can be varied according to signals from a light sensor system providing a visual angle that relatively matches that of the driver. The system allows an automatic darkening of a specific area. However, it requires a sophisticated and expensive sensor system.
One other invention is to provide filtering, such as the use of a liquid crystal display (LCD) screen with camera and sensors to detect the existence and position of a light source. These components, along with the visual detection of the driver, can be used to determine which portions of the LCD screen should be activated to block the light source from the driver's eyes. However, this solution has the disadvantages of being expensive, in that extra sensor and camera hardware is needed to detect not only the driver's eye position, but also the light source position.
A system that selectively attenuates the light passing through an area on an electro-optical element, coated on the windshield, is documented in U.S. Pat. No. 7,134,707 B2. The system consists of a navigation system that determines the vehicle's location and direction of travel, a memory that contains a general location of the driver's eyes within the vehicle, an ephemeris system for providing the position of the sun, and a controller for the calculations. This invention will apply when the light source is in areas not covered by a visor and will perform automatic attenuation of the light passing through the area between the light source and the driver's eyes. Yet, there are a few limitations and complications with this invention. First, the patent does not disclose or describe the details—only the conceptual idea—on how the information from the navigation and ephemeris systems and data on the general location of the driver's eyes are translated into pixels on the electro-optical element. Second, only a generalized location of the driver's eyes is considered in the system. There is no real-time tracking of the driver's eye positions. As indicated in the patent, the driver may have to move his or her head if the light intensity attenuated areas are not in the line of sight between the glare and the driver's eyes. This would be an unnecessary strain on the driver. Third, the system does not consider the slope (inclination or declination) of the road. One of the most dangerous situations for an accident is when there is an abrupt change in the slope of the road and the sun glare will be blinding. Fourth, the patent's method provides only an estimation of the area for opacity to be attenuated because it does not consider the windshield tilt angle, which can vary substantially among different makes and models of motor vehicles.
Accordingly, the present invention offers a new system and method that overcomes the aforementioned problems and drawbacks. Contrary to prior inventions, the present system automatically blocks sun glare on the windshield for motor vehicle drivers under all typical situations and circumstances. This invention details (describes) the method of calculating the sun glare position and changing the opacity of a specific area in the windshield, or the “sun glare block area.” The invention also details the method of calculating and changing the opacity, to a lesser extent than that of the sun glare block area, of the entire area of the windshield, with the windshield acting as the “sunshield.”
3. References
U.S. Patent or Patent Application Documents
4,874,938October 1989Chuang4,892,394January 1990Bidabad5,258,607November 1993Agostini, Agostini, Noli5,271,653December 1993Shirley5,513,892May 1996Thomas6,056,424May 2000DiNunzio6,286,887 B1September 2001Hashmi2002/0130530September 2002Zenisek6,811,201 B2November 2004Naik7,134,707 B2November 2006Isaac7,163,252 B1January 2007Neault2007/0133078 A1June 2007Fanton, Claude, Dubrenat, Schuett
Foreign Patent Documents
JP 2003159942 A2June 2003Motoi, ShunichiDE 102005007427 A1August 2006Sinnhuber, Wohllebe, Jan, Walter